This invention relates to compositions comprising an edible oil, especially to powdered compositions; to methods of producing these compositions; to food products comprising these compositions; and to the use of the compositions.
Edible oils that contain unsaturated fatty acids, and especially polyunsaturated fatty acids (PUFA), usually in the form of glyceride esters, have been shown to have beneficial health effects. These health effects include reduction of cholesterol levels, protection against coronary heart disease and suppression of platelet aggregation. For example, fish oil, which contains the omega-3 and omega-6 fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), has been used in food products and in nutritional products for its health benefits.
PUFA have been incorporated into a matrix. For instance, WO 97/37546 discloses free flowing compositions comprising a fat blend. As a further example, EP-A-1175836 discloses edible fat based flakes containing a fish oil.
One problem with PUFA is that they have a tendency to undergo oxidation and as a result can have an unpleasant taste and/or odour. This tendency also has a negative effect when the PUFA are stored; that is, the shelf or storage stability is relatively short because of the problems associated by the tendency to undergo oxidation.
Conventional powdered fish oils have therefore been treated in a specific way and/or incorporated agents that stabilise the PUFA against oxidation.
For example, WO-94/01001 discloses a microencapsulated oil or fat product on the basis of caseinate as the encapsulating compound. The use of caseinate as the only emulsifying agent optionally in combination with at least one carbohydrate results in relatively stable oil or fat products.
U.S. Pat. No. 3,971,852 describes a process wherein the use of polyhydroxy alcohols as a component within a micro encapsulating matrix can be beneficial to the final powder characteristics of the formed product. A lower surface area and less powder surface discontinuities are a result of this process. However, no special remarks have been made to a better oxidative shelf life of the hereby-obtained products.
U.S. Pat. No. 5,972,395 describes the combination of a minor part of a high molecular weight and a major part of a low molecular weight component within the encapsulating matrix for use in an extrusion process. The low molecular weight component can consist of low melting water soluble carbohydrates, sugar alcohols, adipic acid, citric acid, malic acid, and combinations thereof. However, no specific preference for any of these combinations has been made in respect to enhanced oxidation stability.
The stabilisation of aqueous emulsions containing fish oil using raffinose, trehalose or sorbitol together with a metal ion chelator is disclosed in U.S. Pat. No. 4,963,385. Stable liquid mineral ascorbate compositions and methods of manufacture and use are described in U.S. Pat. No. 6,197,813. The obtained liquid compositions are stabilised against oxidative degradation by the presence of sugar alcohols, sugars, or a metal ion chelator, or combinations thereof. WO 89/02223 describes the use of fructose for the stabilisation of emulsions containing fish oils, such as salad dressings.
It has also been suggested to stabilise fish oil with cyclodextrin, see, for example, U.S. Pat. No. 4,438,106. In a further development, U.S. Pat. No. 6,638,557 seeks to reduce the amount of cyclodextrin that is used in a composition containing an edible oil and starch by employing a converted starch and a starch hydrolysate in the composition. The starch hydrolysate is a maltodextrin or a thin boiled starch. These components can increase the viscosity of the composition before it is processed into a powder. This increase in viscosity can be a disadvantage in powder production.
It is known that some simple carbohydrates are potential hydroxyl radical scavengers in liquid compositions. See in this respect Int. J. Food Sciences and Nutrition, 2002, 53, 419 423 and J. Agric. Food Chem., 2003, 51, 7418-7425.
Further examples of conventional powdered fish oil containing agents that stabilise the PUFA against oxidation are described in JP-A-8-259944. This document discloses the use of sugar alcohols, such as mannitol, as oxidation stabilisers for emulsified oil or fat. Similar disclosures can be found in JP-A-8-259943 and JP-A-8-051928.
However, various disadvantages are to be expected employing the oxidative stabiliser as described in JP-A-8-259944. For instance, the high amount of mannitol, being a sweetener, within the described compositions can negatively affect the taste.
Furthermore, sugar alcohols such as mannitol are known for their laxative effect. Initial laxative threshold of mannitol varies between 20-40 g/day, although the accepted daily intake (ADI) of mannitol has not yet been specified by WHO (1987). The use of mannitol as described in the JP-A-8-259944 application to stabilise emulsified oil or fat is from an economical point of view also not preferred. The associated costs of polyols, e.g. mannitol, put limitations on the use according to JP-A-8-259944. Essentially, the use of mannitol in the way as taught in the prior art is disadvantageous because of both the cost issue and the limitations associated with laxative effects. These two disadvantages associated with the use of mannitol are even more profound when mannitol is used with the intention to increase the stability and shelf life of compositions containing low cost oils such as linseed oil, soya oil, sunflower oil or rapeseed oil. These type of compositions are generally used in relatively large quantities as a food ingredient in numerous food applications, generally consumed in relatively large amounts.